Broadcasting stations, for example, have traditionally made use of video signal editing apparatuses for reading a video signal of a digital format from a video tape or a hard disk and editing the same for producing a video for news, for example.
Some video signal editing apparatuses use a video tape as a recording medium. A video tape is superior in the point that it can record a video signal of a long duration, but does not allow random access of any portion of the video signal.
Other video signal editing apparatuses use a hard disk as the recording medium. A hard disk is excellent in random accessibility and therefore allows large numbers of portions of a video signal to be read in a short time. However, at the present time, it does not allow recordal of a video signal as long in duration as with a video tape.
Accordingly, it is convenient to use a video tape and a hard disk in association, first record the long duration video signal which is shot on the video tape, then find and move only the portion in the video signal recorded on the video tape necessary for the actual editing to the hard disk and read the relevant portions from the hard disk for use for the editing work.
As mentioned above, it is convenient to use a video tape and a hard disk in association during editing work, but it takes a lot of work to find the portions necessary for the editing from the long duration video signal recorded on the video tape.
That is, the editor is required to find the portions necessary for editing by reproducing the video signal while fast forwarding (FWD) or rewinding (REV) the video tape and moving those portions to the hard disk. A long time and much labor are taken for this work.
To facilitate this work, there is known for example the "Method of Fetching Editing Information" disclosed in Japanese Examined Patent Publication (Kokoku) No. 61-44437. This method reduces in size and successively displays on a single screen the frame of a video signal reproduced at a certain point of time and the several frames of the video signal reproduced before it to thereby provide an environment for editing a video of equal detail as when editing movie film.
With the method disclosed in Japanese Examined Patent Publication (Kokoku) No. 61-44437, however, even though it is possible to display several adjoining frames of a video signal being reproduced at a certain point of time, it is not possible to fetch and display from the video tape as a whole a broader range of the video signal, for example, just the portions of the video signal where the scenes change.
Further, for example, Japanese Examined Patent Publication (Kokoku) No. 61-44437 describes a method of reducing in size and displaying on a single screen a plurality of images at the boundaries of scenes in a video signal.
However, Japanese Examined Patent Publication (Kokoku) No. 61-44437 does not specifically disclose how to detect the boundaries of the scenes in a video signal. Further, with this method, it is not possible to designate important portions included in a scene.